When a photograph or another picture is taken of a desired object, there is a need to illuminate said object. By means of the illumination the taken picture is of considerably better quality than a picture taken of a non-illuminated object. For instance, the contours of the object to be photographed are more distinguishable by illuminating the object.
Appropriate illumination of an object is particularly important in medicine, for instance, when eyes are examined. FIG. 1 shows a prior art solution for taking pictures of eyes 120. In photographing it is possible to take a picture of the eye surface with a purpose-made device 100. The picture is formed on the basis of how a light ray directed to the eye 120 on the optical axis 110 of a camera lens 106 in a camera unit 100 reflects back from the surface of the eye 120. In order to obtain a desired picture of the eye 120, it is important to illuminate the object. The eye 120, and possibly also the area around it, may be illuminated by an illuminating device 102.
A problem is that the pictures easily show bright reflections that typically appear in pictures taken of a spherical reflecting surface such as a cornea 126 of the eye and an iris 124 around the pupil 122. In addition, human skin may also cause undesirable reflections, when the object is illuminated by a flash light 104. Reflections of the flash light 104 may mask features that should be recorded on picture. However, it is difficult, in practice, to take pictures without the flash light 104, because the camera 100 is to be close to the object and consequently access of light from the environment to the surface of the object is strongly inhibited. In addition, it is difficult to record small features on the pictures, because it is difficult to keep the distance constant and the camera 100 will jolt easily. For examining the surface parts of the eye the doctors also use a so-called slit lamp 100, in which the camera may be connected to a table stand. This makes it possible to avoid jolts, among other things. Slit lamps are relatively large in size, and it is not easy to move them.
It is important to produce pictures of the object to be examined, in which disturbing reflections and/or jolts do not appear.